The Oracle Database Resource Manager can be used in many ways, such as managing CPU, I/O, parallel execution, runaway queries, etc. This note addresses issues that are specific to managing CPU.
CPU Resource Manager is enabled when the current Resource Plan contains CPU management directives. These directives are called cpu_p1, cpu_p2, cpu_p3, etc. in releases prior to 11.1. They are called mgmt_p1, mgmt_p2, mgmt_p3, etc. in 11.1 and all subsequent releases.
When using CPU Resource Manager, 3 types of issues are seen:

Below is a list of the most critical, known bugs for CPU Resource Manager. These bug fixes are recommended for all customers that are either evaluating or using CPU Resource Manager.

For other recommended bug fixes, monitoring scripts, and other tips for Resource Manager, see the master MOS Document 1339769.1.

Bug

Bug Description

Recommended Releases

Bug 6874858

CONNECTION TIMEOUT WHEN RMAN BACKUP RUNINGResource Manager under-utilizes the CPUs. This bug occurs with workloads that contain a lot of sequential I/Os.

10.2.0.4

Unpublished bug 8793492

INSTANCE CAGING LETS TOO MANY ORACLE FOREGROUND PROCESSES RUNNING PERIODICALLYThe name for this bug is misleading, as it also occurs when Instance Caging is not used. The symptom is long wait times for “library cache: mutex X”, resulting in excessive CPU utilization.

11.1.0.7
11.2.0.1 (fixed in Exadata BP7)

Unpublished bug 6431266

TURN OFF QUANTUM DONATION: PLAN CONFORM DISPARITY + HIGH THRESHOLD BASED ON LOWThis fix improves the accuracy with which Resource Manager enforces the resource allocations specified in the Resource Plan.

10.2.0.4

Unpublished bug 8636407

INSTANCE CRASH DUE TO INTERNAL ERROR ENCOUNTERED BY PMONThe symptom of this bug is ORA-600[kgskexitsch]. It is a very intermittent bug that can result in instance crashes.

10.2.0.4
10.2.0.5 (fixed in PSU6)
11.1.0.7 (fixed in PSU10)
11.2.0.1

Bug 10039731

HIGH WAITS FOR RUNNABLE PROCESS USING PX AND RESMGRResource Manager under-utilizes the CPUs. This fix addresses the under-utilization. It also improves the accuracy with which Resource Manager enforces the resource allocations specified in the Resource Plan.

SINCE APPLYING PATCH FOR 8624887 “UNSPECIFIED WAIT EVENT” IS SEEN IN AWRThis bug causes Resource Manager to under-utilize the CPUs. This bug can also result in a large number of “unspecified” wait events.

DBMV2: ORA 600 [RESPLAN:TRYADD_3] IN THE CELL SIDE WITH GE/DBFS WORKLOADThis bug only occurs on Exadata systems. The symptom is a storage cell crash with the error ORA 600 [RESPLAN:TRYADD_3]. The workaround is to avoid using Resource Plans with subplans, such as the “default_maintenance_plan”, which is enabled during the maintenance windows.

CPU CONSUMED TIME DOES NOT TAKE ACCOUNT OF SHORT WAITSThis bug only affects the Resource Manager statistics. The Resource Manager statistics for “cpu consumed” is too low. It doesn’t include CPU consumed during short waits.

11.2.0.1
11.2.0.2 (fixed in Exadata BP 10)

Unpublished bug 7414919

CONSUMED_CPU_TIME IN SYS_GROUP IS INCORRECTLY REPORTEDThis bug only affects the Resource Manager statistics. The reported value of v$rsrc_consumer_group.consumed_cpu_time is too high.

10.2.0.4

Unpublished bug 12420002

LNX64-11203-RAC:DB HIT ORA-700 [KGSKRECALC:RECALCRUNCOUNT1]This bug can cause intermittent errors. The symptoms of this bug are ORA-600 [kgskewtx] or ORA-700[kskplanresetact] or ORA-700 [kgskrecalc:recalcruncount1] or ORA-600[kgskrunnextint:state].

10.2.0.4
10.2.0.5
11.1.0.7
11.2.0.1
11.2.0.2

Unpublished bug 10219583

DBMV2: DATABASE HUNG AFTER 4 HRS OF ENABLE/DISABLE IORMPLAN
This bug only occurs on Exadata. It can cause the database to hang when Resource Manager plans are being set while smart scans are running. This bug occurs very intermittently.
The workaround is to avoid changing database resource plans while workloads are running.